In general, an organic light-emitting device (hereinafter, referred to as OLED) comprises a substrate, an anode positioned on the substrate, an emission layer positioned on the anode, and a cathode positioned on the emission layer. In the OLED having the above structure, when a voltage is applied between the anode and the cathode, holes and electrons are injected into the emission layer, and then combined in the emission layer to create exitons, which decay radiatively. This radiation is called electroluminescence (EL)
A fabrication method of a conventional full-color OLED includes forming emission layers corresponding to red (R), green (G) and blue (B), respectively. But in this method, the emission layers have different lifetime characteristics one from another, so that it is difficult to maintain white balance when they are driven for a long time.
To solve this problem, U.S. Pat. No. 6,515,428 discloses an OLED with a color filter (hereinafter, referred to as CF) formed by a photolithography process and an emission layer for emitting white color light. However, forming the CFs of R, G and B color by the photolithography process requires repeating the process of spin coating the CF material of each color, as well as exposing, developing, and patterning. In these processes, a CF previously formed may be contaminated by a CF material of another color which is spin coated on the CF. Furthermore, a thermal process should be performed to remove any volatile solvent, etc., contained in the CF formed by the photolithography process. Thus, forming the CF by the photolithography process has a disadvantage of requiring many processes and more time to fabricate the OLED.
U.S. Pat. No. 6,522,066 discloses an OLED with a color conversion medium (hereinafter, referred to as CCM) formed by the photolithography process and an emission layer for emitting blue color light. The problems associated with forming the CCM by the photolithography process are often the same as those associated with forming the CF.
To solve the above problems, Korean patent application number 2001-0000943 discloses an OLED including CFs or CCMs formed by a vacuum deposition process. However, forming the CFs or the CCMs using the vacuum deposition process is performed by respectively depositing layers corresponding to the R, G and B using metal masks. This makes it hard to implement a high resolution due to difficulties aligning between the metal mask with the substrate. A further disadvantage is that the layers corresponding to the R, G and B are deposited in a separate chamber, respectively, significantly increasing an equipment investment.